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<TITLE>Canonical XML</TITLE>
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<H1>Canonical XML</H1>
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This document defines a subset of XML called canonical XML.
The intended use of canonical XML is in testing XML processors,
as a representation of the result of parsing an XML document.
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Every well-formed XML document has a unique structurally equivalent
canonical XML document.  Two structurally equivalent XML
documents have a byte-for-byte identical canonical XML document.
Canonicalizing an XML document requires only information that an XML
processor is required to make available to an application.
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A canonical XML document conforms to the following grammar:
<PRE>
CanonXML    ::= Pi* element Pi*
element     ::= Stag (Datachar | Pi | element)* Etag
Stag        ::= '&lt;'  Name Atts '&gt;'
Etag        ::= '&lt;/' Name '&gt;'
Pi          ::= '&lt;?' Name ' ' (((Char - S) Char*)? - (Char* '?&gt;' Char*)) '?&gt;'
Atts        ::= (' ' Name '=' '"' Datachar* '"')*
Datachar    ::= '&amp;amp;' | '&amp;lt;' | '&amp;gt;' | '&amp;quot;'
                 | '&amp;#9;'| '&amp;#10;'| '&amp;#13;'
                 | (Char - ('&amp;' | '&lt;' | '&gt;' | '"' | #x9 | #xA | #xD))
Name        ::= (see XML spec)
Char        ::= (see XML spec)
S           ::= (see XML spec)
</PRE>
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Attributes are in lexicographical order (in Unicode bit order).
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A canonical XML document is encoded in UTF-8.
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Ignorable white space is considered significant and is treated equivalently
to data.
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<ADDRESS>
<A HREF="mailto:jjc@jclark.com">James Clark</A>
</ADDRESS>

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